Board of Adjustment Agenda and Packet 2011 08 17

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1303 Empire Road Floodplain 2 The FEMA manual titled "Managing Floodplain Development in the Approximate Zone A Areas", dated July, 1995 (FEMA Publication 265) provides guidance for community officials, property owners, developers, surveyors, and engineers in determining the base flood elevations and proper flood protection requirements for development within Zone A areas. The FEMA guidelines have been utilized in the analysis of the existing floodplain zoning and the preparation of this report. Review of the FIRM Panels 557 and 576 show that the 1303 Empire Road property is located in a special flood hazard area that originates west of State Highway 42 (Courtesy Road) in old town Louisville, and is known locally as Drainageway A. Drainageway A has historically created flooding conditions in the downtown Louisville area, and in the 1990's was the cause for a drainage and flood mitigation project by the City of Louisville and the Urban Drainage and Flood Control District. The project constructed a detention pond at Middle School Park and a 60-inch storm sewer pipe to an outfall point on the east side of State Highway 42, just south of where Short Street terminates. As a result of the mitigation project, FEMA approved a Letter of Map Revision (LOMR) in 2000 that modified the Special Flood Hazard Area for Drainageway A. Although the LOMR resulted in a substantial reduction in the downtown Drainageway A 100- year floodplain, an area of Zone AH (flood depths of 1 to 3 feet, usually due to ponding) remains in the downtown area. The Zone AH floodplain is created by a sump condition that extends to the Burlington Northern Railway embankment to the east. From the railway embankment eastward to State Highway 42, areas subject to inundation from flows that overtop the railroad tracks are mapped as a Zone AE area (an area where base flood elevations have been determined). From State Highway 42 eastward, the flood hazard area remained unchanged from the original mapping as the Zone A area that the 1303 Empire Road property is located in. The Zone A area east of State Highway 42 was not modified as part of the Drainageway A LOMR revisions. Consistent with FEMA map revision policies requiring smooth boundary transitions between new and old flood zones, it appears that the Zone AE area between the railway embankment and State Highway 42 was used a the transition area from the revised downtown Zone AH flood hazard boundaries to the unrevised Zone A areas east of Highway 42. No regulatory floodway has been identified or mapped for the Drainageway A floodplain, nor is it anticipated that a floodway will need to be identified or mapped as part of future floodplain studies or improvements. Applicable City of Louisville Floodplain Regulations The City of Louisville floodplain regulations are contained in Section 17.56 of the Louisville Municipal Code. Section 17.56.070 of the code states that the location and boundaries of the flood regulatory district are as identified by the FEMA Flood Insurance Study and FIRM panels for the city, and Section 17.56.200 states that a floodplain development permit is required and must be obtained from the board of adjustment before any new land use, construction, or development begins within the flood regulatory district or area of special flood hazard. 7115 Dry Creek Court Niwot, Colorado 80503 Phone: 720-231-3251 CURTPARKER55@hotmail.com